does not work check if dead

Of cource! there is a code. If the player leaves the camera at a height of - 6f isDead = true; game$$anonymous$$anagerScript.GameOver ();

 using UnityEngine;
 
 public class PlayerController : $$anonymous$$onoBehaviour {
 
     public Transform cameraTrans;
 
     public Game$$anonymous$$anager game$$anonymous$$anagerScript;
 
     public int score = 0;
 
     float playerFirstYPos;
 
     [SerializeField]
     float moveSpd;
 
     [SerializeField]
     float jumpPower;
 
     Rigidbody2D myRigidbody2d;
     SpriteRenderer mySpriteRenderer;
 
     bool isDead = false;
 
     void Awake(){
         
         myRigidbody2d = GetComponent<Rigidbody2D> ();
         mySpriteRenderer = GetComponent<SpriteRenderer> ();
     }
 
     void Start(){
 
         playerFirstYPos = transform.position.y;
 
     }
 
     void Update(){
 
         FlipCharacter ();
         CheckIfDead ();
         SetScore ();
     }
 
     void FixedUpdate (){
 
         Vector3 pos = myRigidbody2d.position;
 
 
 
         pos.x = $$anonymous$$athf.Clamp (pos.x, -2f, 2f);
 
         myRigidbody2d.position = pos;
         //if delete go control touch
         myRigidbody2d.AddForce (Vector2.right * Input.GetAxis ("Horizontal") * moveSpd);
         //if delete go control touch
         if (Input.touchCount > 0)
         {
             Touch touch = Input.GetTouch(0);
             float middle = Screen.width / 2;
             if (touch.position.x < middle)
             {
                 myRigidbody2d.AddForce (Vector2.right * -1 * moveSpd);
                 mySpriteRenderer.flipX = true;
             }
             else if (touch.position.x > middle)
             {
                 myRigidbody2d.AddForce (Vector2.right * 1 * moveSpd);
                 mySpriteRenderer.flipX = false;
             }
         }
         else
         {
             
         }
             
 
     }
 
     void OnCollisionEnter2D(Collision2D col){
 
         if(col.gameObject.CompareTag("Jumpable")){
             
         myRigidbody2d.velocity = new Vector2 (myRigidbody2d.velocity.x, 0f);
         myRigidbody2d.AddForce (Vector2.up * jumpPower);
     }
     }
 
 
     void FlipCharacter(){
 
         if (Input.GetAxisRaw ("Horizontal") < 0)
             mySpriteRenderer.flipX = true;
         else if (Input.GetAxisRaw ("Horizontal") > 0)
             mySpriteRenderer.flipX = false;
 
     }
 
 
     void CheckIfDead(){
         if(transform.position.y <= cameraTrans.position.y - 6f && !isDead) {
             isDead = true;
             game$$anonymous$$anagerScript.GameOver ();
 
         }
     }
 
     void SetScore(){
 
         score = $$anonymous$$athf.$$anonymous$$ax (score, $$anonymous$$athf.FloorToInt (transform.position.y - playerFirstYPos) * 10);
 
     }
 }